“That’s two games in a row that we got behind and it’s unacceptable,” Babcock said.

The Red Wings (33-26-14, 80 points) couldn’t capitalize on an opportunity to move past three teams they’re tied with for the first wild-card playoff spot in the Eastern Conference.

They are winless in three (0-2-1) and suffered their first regulation loss at home since Jan. 20 (they were 8-0-3 in the past 11).

Babcock second-guessed himself for giving the team an optional practice Wednesday, when only a few players skated.

“Looked like we couldn’t skate at the start of the game,” Babcock said. “You can bet it won’t be an optional tomorrow.”

Riley Sheahan said it’s difficult to determine whether the day off hurt them.

“Guys are usually pretty good at making sure their legs are ready, especially this time of year,” Sheahan said.

The Red Wings came back strong in the third period, tying it at 3-3 on a pair of goals by Tomas Tatar just 3:06 apart early in the third period. Tatar intercepted a poor clearing attempt by P.K. Subban and fired a shot from the slot past Carey Price at 1:24. He took a pass from Tomas Jurco and scored at 4:30.

Problem was, the good feeling didn’t last long, as Max Pacioretty gave Montreal the lead for good at 5:48, on a shot that deflected in off Niklas Kronwall’s skate, on a play that was off-sides.

“The way I look at it is you earn your own breaks,” Babcock said. “We put ourselves in a bad spot by getting behind early. The referees and the linesmen are trying to do it right.”

Vanek redirected a pass from the slot past Jimmy Howard at 11:15 to make it 5-3, but Johan Franzen answered quickly at 11:36 with his first goal in 10 games. The Red Wings still had plenty of time, but couldn’t complete the comeback.

“You’ve got to give guys credit, they battled like crazy,” Babcock said. “Our kids were outstanding. We didn’t have enough veteran guys going here tonight and we have to be better than that.”

Babcock said his team missed too many simple assignments that led to goals.

“I thought we played good and had lots of opportunity offensively,” Babcock said. “We were just poor in our own zone on sort-outs, on face-offs, which is just an easy thing to do.

“But my big thing here today is catch-up hockey is losing hockey. You’ve got to get prepared, you’ve got to play right and you have to do it for 60 minutes and be patient. When you start chasing the game like we were anything can happen. It’s entertaining for the fans but it’s not a recipe for success whatsoever.”

Tomas Plekanec scored twice in the first period, at 5:14 and 14:11, to put the Canadiens ahead. Sheahan got one back at 1:28 of the second, but David Desharnais gave Montreal a 3-1 lead at 11:03.

“We weren’t very good in the first period, starting with myself,” Kronwall said. “We were turning the pucks over all over the ice, we weren’t skating and we weren’t working.

“But in saying that we were still in the game somehow. Howie kept us in there, gave us a chance.”

Babcock defended Howard, who allowed five goals in 29 shots.

“I thought we made mistakes. I didn’t think we were good. I didn’t think we played well enough,” Babcock said. “So it was a huge game for us and we didn’t get it looked after. We’ve got to get ready here tomorrow, we’re going to Toronto and we have to get it looked after there. But this having a day off, having fresh legs and not being able to skate is unacceptable.”

The Red Wings have nine games remaining, including a big one Saturday night in Toronto, against a club that has lost six in a row to drop even with Detroit.